Expression analysis of the mouse RNase III transcript. A. RT-PCR analysis of the RNase III transcript in adult mouse organs, in day 13.5 (E13.5) mouse embryo ("Embryo"), and in extra-embryonic organs ("Placenta" and "Yolk Sac"). Analysis was performed as described in Materials and Methods. The 272 bp PCR product was generated using an oligodeoxynucleotide pair that localized to a sequence in the dsRBM (forward primer) and 3'-UTR (reverse primer). For each lane, a separate RT-PCR analysis which omitted reverse transcriptase did not provide a DNA product (data not shown). The lower panel displays a control experiment showing uniform production of a β-actin mRNA-specific PCR product (100 bp). DNA size markers are provided in lane M. B. Northern analysis of the RNase III transcript. A 32P-labeled, 1.2 kb probe specific to the 3' region of the RNase III sequence (cDNA clone accession no. AA549506) was hybridized to a multiple tissue northern blot. Each lane contained 2 μg of poly(A)+ RNA from the indicated adult mouse organs (upper panel). The blot was visualized by phosphorimaging. The actin control blot is shown in the lower panel. The 1.8 kb transcript in the heart, skeletal muscle and testis lanes represents an alternatively processed actin RNA.